Hop plants comprise a variety of natural compounds greatly differing in their structure and properties. A wide range of methods have been developed for their isolation and chemical analysis, as well ...as for determining their antioxidative, antimicrobial, and antigenotoxic potentials. This contribution provides an overview of extraction and fractionation techniques of the most important hop compounds known for their health-promoting features. Although hops remain the principal ingredient for providing the taste, stability, and antimicrobial protection of beer, they have found applications in the pharmaceutical and other food industries as well. This review focuses on numerous health-promoting effects of hops raging from antioxidative, sedative, and anti-inflammatory potentials, over anticarcinogenic features to estrogenic activity. Therefore, hops should be exploited for the prevention and even healing of several prevalent diseases like cardiovascular disorders and various cancer types. New ideas for future studies on hops are finally presented: computational investigations of chemical reactivities of hop compounds, nanoencapsulation, and synergistic effects leading to a higher bioavailability of biologically active substances as well as the application of waste hop biomass from breweries for the production of high-added-value products in accordance with the biorefinery concept.
Hop cones (Humulus lupulus L.), or more specifically the lupulin glands, hold the reason for the specific, pleasant aroma of hops - its essential oil. The hops themselves, or the extracted oil, are ...used almost exclusively in beer production. The essential oil is an indispensable part of beer and is responsible for its characteristic aroma. However, hop essential oil (HEO) also has a broad range of positive effects on human health and is a potential natural pesticide that has no harmful impacts on humans. This review summarizes basic information about HEO, including its chemical composition and methods for extraction and analysis, while also providing a comprehensive overview of the contribution to beer aroma, health, and insecticide applications for this versatile essential oil.
A need exists for a reliable method to determine the geographical and botanical origin of hops. For this study, three sets of samples were collected: the first set comprised 5 German samples; the ...second set comprised samples of hops from 10 of the world’s major hop-growing regions; and the third comprised the 4 main Slovenian regions. The samples were analyzed using isotope ratio mass spectrometry (IRMS) to obtain δ13C, δ15N, and δ34S values. The δ15N (2.2 ‰ to 8.4 ‰) and δ34S (0.7 ‰ to 12.3 ‰) values were the most discriminating parameters for classifying hop according to geographical origin. ANOVA showed distinct groupings for 8 out of the 10 hop-growing regions. Although it was not possible to distinguish the geographical origin of hops based on δ13C (−28.9 ‰ to −24.7 ‰), in the case of botanical origin, δ13C values proved to be the most discriminative albeit with limited success.
Two samples of tartary buckwheat (Fagopyrum tataricum Gaertn.) from China and one from Luxembourg were studied by high-performance liquid chromatography (HPLC) to reveal the possibilities of growing ...tartary buckwheat herb as a possible source of rutin, quercetin, and quercitrin. The content of rutin was determined as up to 3% dry weight (DW) in tartary buckwheat herb. Quercitrin values were in the range of 0.01−0.05% DW. Only traces of quercetin were detected in just some of the samples. Tartary buckwheat seeds contained more rutin (about 0.8−1.7% DW) than common buckwheat seeds (0.01% DW). Rutin and quercetin content in seeds depends on variety and growing conditions. Tartary buckwheat seeds contained traces of quercitrin and quercetin, which were not found in common buckwheat seeds. Keywords: Tartary buckwheat; antioxidants; flavonoids; rutin; quercetin; quercitrin
In 2019, we conducted a field experiment to test the effects of three different granular fertilizers on the salicylic acid and total phenolic contents in five different sport turfgrass mixtures under ...natural conditions. It was one of the first experiments assessing the natural resistance of sport turfgrass in Europe. In five terms, before and after fertilizers applications, we randomly collected turfgrass samples within each plot for chemical analyses. The turfgrass mixtures did not affect the average contents of salicylic acid and total polyphenols. The average contents of both compounds were influenced by the date of evaluation and fertilization scheme. The average content of salicylic acid was significantly the lowest under fertilization scheme C. The highest level of salicylic acid was detected on 18th June under scheme A and the lowest on 28th May, where the salicylic acid content ranged from 0.01 ± 0.00 mg.g
−1
under scheme A to 0.017 ± 0.00 mg.g
−1
under scheme B and 0.006±0.00 mg.g
−1
under scheme C. The content of total polyphenols was higher under fertilization schemes B and C. We conclude that the method of fertilization exerts a certain effect on the salicylic acid and total polyphenol contents in turfgrass mixtures, which also depends on environmental factors.
The authors would like to state that they inadvertently omitted one of the authors
when preparing the manuscript. The authors of this work are as follows:
Miha Ocvirk1, Nataša Kočar Mlinarič2, Peter ...Raspor3 and Iztok Jože Košir1*
1Slovenian Institute of Hop Research and Brewing, C. Žalskega tabora 2, 3310 Žalec, Slovenia
2Pivovarna Laško Union d.o.o., Pivovarniška ulica 2, 1000 Ljubljana, Slovenia
3Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
•Multi-elemental fingerprinting can be used for determination of geographical origin of hops.•The most significant parameters in the discrimination were Si, Ti, Fe and Sr.•Effective differentiation ...between European and non-European was achieved.
For brewers, it is important to know the geographic origins of the hop plants (Humulus lupulus L.) used in their brewing processes since the contents and compositions of the bitter resins and essential oils in them depend on the environmental conditions during their growth. In this study, the multi-elemental profiles of hop plants from each of the world’s main growing regions were determined by non-destructive energy dispersive X-ray fluorescence spectrometry (EDXRF). Understanding the multi-element profiles of the plants could be a useful tool in determining the geographic origins of produced hop plants.
Hops are an indispensable ingredient in beer, and the differences in their chemical composition impart the various tastes and aromas associated with different beers. However, during storage, hops ...undergo changes in their chemical composition. Here, the changes in aroma and bitterness of kettle-hopped beers were evaluated in an experiment conducted on three different hop varieties (Aurora, Celeia and Styrian Wolf) with five different hop storage index (HSI) values (0.3-0.7). Hops were added to boiling wort for 5, 45 and 90 min. Alpha-acids, iso-alpha-acids, humulinones, bitterness units and hop aroma compounds in the samples were chemically analysed. All samples also underwent sensorial analysis. The old hops were not problematic in terms of bitterness or early hopping time. However, later additions of old hops reduced the quality and intensity of the hop aroma. The limit value for use without negative consequences for kettle hopping was set at HSI 0.5 for Aurora and Celeia and HSI 0.6 for Styrian Wolf.
Hop essential oil, in addition to alpha-acids, is one of the most valuable parameters for brewers, since it is responsible for beer aroma. The hop oil content and hop oil chemical composition deliver ...various aromas to beer. During storage, the hop chemical composition undergoes many physical and chemical changes that impact its quality. The main purpose of our study was to evaluate the changes occurring in hop oil content and its chemical composition during two years of storage under four different conditions (anaerobic, aerobic, cold room (4 °C), and room temperature) in the form of cones and pellets, supplied by local suppliers in Slovenia. Hop oil content and composition were determined by steam distillation and GC-FID. The greatest decrease in hop essential oil content occurred when the hops were stored under aerobic conditions and at room temperature. Monitoring of eight hop oil compounds under various conditions revealed different behaviors of the changes. The best storage conditions were anaerobic at low temperatures. Oxygen resistance was lower for pellets than for hop cones, whereas high temperature was more devastating for hop cones. In addition to the storage conditions, the hop variety and form were important factors regulating the extent of changes in hop oil content and chemical composition.
The stability of alpha-acids, beta-acids and hop storage index (HSI) values under different conditions (aerobic/anaerobic, 4 °C/room temperature) was studied in a two-year trial. Six different ...varieties (Celeia, Aurora, Bobek, Styrian Gold, Savinjski Golding and Styrian Wolf) were used in the form of cones and pellets. Alpha- and beta-acids were determined by HPLC and HSI by spectrophotometry. Anaerobic conditions at 4 °C were best for alpha-acids, beta-acids and HSI values; however, 10-35% of the alpha-acids were still lost after two years. The decline was greater (63-99%) under aerobic conditions and at room temperature. Alpha-/beta-acid ratios increased in hop cones and decreased in hop pellets, whereas HSI values increased in all storage conditions. Overall, the performance was better for pellets than for hop cones. Storage conditions, storage form and hop variety had significant effects on the stability of hop resins.
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